nifty HYBRID DC HR15N Series, Service Manual

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47
English 07/16
Service Manual
HR15/17N HYBRID DC
5.6 Hydraulic System Overview
A simplified version of the hydraulic system is shown below in block diagram format. Brief descriptions
of the operation of individual blocks are given below. Component details, valve arrangement and
connections are shown in the hydraulic schematics D81900 (Hybrid) and D81500 (DC Electric). Please
refer to D81900/D81500 in conjunction with the electric schematic D81619 for in-depth understanding of
the complete system.
5.7 Load Sensing Pump
The Niftylift is fitted with an 10.5CC (Hybrid) 8CC (DC Electric) variable displacement pump (open loop
load sensing). Standby pressure and maximum pressure are set to 17 bar (247 psi) and 280 bar
(4061 psi). The load sense signal is obtained either from the boom control valve or from the drive control
valve. The tank is pressurised up to 1.3 bar (18.85 psi) absolute to allow positive head at the suction port.
Note that if any maintenance is carried out on the hydraulic system, undo the filler cap on top of the tank
to remove the pressure from the tank, this will reduce leakage from the tank ports. The pump runs at fixed
preset speeds and swash angle/pressure varies according to the flow demand and load pressure.
DRIVE
CONTROL
VALVE
STEER CYLINDER
WHEEL MOTORS
REAR
BRAKE RELEASE
REAR
BOOM
CONTROL
VALVE
DIFFLOCK
VALVE
HAND
PUMP
PILOT
JOYSTICK
VARIABLE
DISPLACEMENT
PUMP